Steam-generator.



No. 848,564. PATENTED MAR. 2G, 1907. W. MITCHELL.

STEAM GENERATOR.

APPLICATION FILED JAN.25, 1905. RBNEWED AUG. za, 1906.

2 SHEETS-SHEET 1.

nuoooononoouoounou-qnuouquunnv, nonaunoqounquucunooooo o nuo one o xoaaoooonqoooon ouun onen No. 848,564. PATENTED MAR. 26, 1907. W. MITCHELL.

STEAM GENERATOR.

APPLICATION FILED JAN.25, 1905. RENEWED AUG. 28, 1906.

2 SHEETS-SHEET 2.

ibm TUMMJ- UNITED STATES PATENT OFFICE.

STEAM-GENERATOR.

Specification of Letters Patent.

Patented March 26, 1907.

Application filed January 28,1905. Renewed August Z8, 1906. Serial No. 332.389.

To all 'whom it 71u14/ concern:

Bo it known that I, WILLIs MITCHELL, a citizen of the United States, residing at Malden, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Steam-Generators; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The chief object of this invention is to generate the greatest practicable quantity of steam from a given amount of' liquid fuel by insuring the perfect combustion of the latter and the application of the caloriiic gas or vapor to the water-tube in the most advantageous manner, incidentally dispensing with a chimney-flue, since the products of combustion are nearly all consumed, and the draft may escape into an apartinent without being offensivi-x These generators embodying my invention are equally available for supplying 'engines or sieam-heating systems or any other machine or apparatus where steam is required.

rlo the above ends my invention consists in the. construction and combination of. parts hereinafter more particularly set forth and claimed.

ln the accompanying drawings, Figure l represents a central vertical longitudinalsection through a steam-generator embodying my invemion. Fig. 2 represents, looking to the right, a vertical cross-section of the same,l

taken just beyond the water-pipe helices on the line 2 2 of Fig. 1.` Fig. 3 represents a dotail view of the collared rod or solid cylinder which forms part of the gas-venerator- Fig. 4 represents a detail View of a sleeve for holding the valve-operating pinion in place. Fig. 5 represents a detail view of one .of the grooved tubessupports. Fig. 6 represents a detail view of one of the hollow tube-supports, partly broken away to show the interior passages. lfig. 7' represents a bottom View of the generati r-casing with the door of the opening for ignition turned aside.

A designates the. generator-casing, preferablycylindrical,or approximatelyfso, in form; B, the inclosed water-tnbe coiled into concentric heliccs of any convenient number, only two, however, being shown; (l, a builner fastened to the interior ol' the front wall (L of the said casing an'd extending throngh the low.

and arranged concentrically, as a hollow core, within the said water-tube helices, and D, a mixing-chamber of elongated cylindrlcal form, arranged concentrically within the said burner, open at both ends and supported at its forward end by said front wall a, through which it barely extends, the rear end of the said mixing-chalnlier being suspended by means of a screw d from the upper part ofthe wall of said burner or supported by any equivalent means and in any equivalent manner. That end of the said casing which is nearest the jet-hole hereinafter mentiondis herein referred to as the front or forward end, the other being called the rear7 end. The same distinction holds with regard to the generator and burner.

The burner C aforesaid is provided with many small discharge-apertures c in longitudinal series, as long as the helices, all said apertures being preferably below the central horizontal plane of the burner and divided into two portions on each side of its Vertical central longitin'linal plane in order that the jets of burning gas may be directed oblirpiely downward to right and left upon the lower parts of the helices. The only outlet from said casing is through a longitudinal trough or tube E on the bottom thereof and communicating therewith by slots c, the rear end c of said tube beingl open. The divergence of the discharge of the heater prevents it from impinging on said outlet-tube or interfering with the ilow through the said openings. There being no llue at the top oi the generator, the heat from such discharges ascends partly through the coils, but more especially through the space F between the outer helix and the casing, and becomes concentrated by the connection of currents in the upper part of the said space, where it will be applied to the upper parts of the helices about as intensely as it has been applied to the parts be- 'lhis e pialization of action is important, and some kind of storage space at the top of the casing is nearly indispensable to it. The cylindrical space or :neuinnlator is the most available form, as it facilitates access ol' the ascending heated currents to the lateral parts ol' the outer helix and also provides for accumulation and` concentration ol' heat in contact therewith. 'lhree kinds oll supports are used for the said helices-solid bars (l, arranged at top .and bottom between the outer helix' and the casing, hollow bars Il,

rear wall n lhereo'l', being closed at bol h ends 1 arranged similarly at intermediate points fol' IVO the passage of gas, andrgrooved bam I, interposed at regular intervals between each two proximate'helices. Each of these bars or su ports'of whatever kind extends longitudinaiiy from end to end of the casing A, being attached to and supported by the end walls thereof. Collectively they hold the helices rigidly in place, maintaining absolutel unchanged the space F and the interva between them. In addition, the supports I hold the individual coils of each helix at equal distances apart, the said coils being set into the grooves 'i of said supports and between their alternate projections I. The

hollow bars H extend from end to end of the cmsing A. Each of them is provided with transverse p h through it for the upward passage of the heated products of combustion in order that these may not be impeded uselessly in reaching the top of the steam-generator. A partition h' separates these pass and preserves the strength of the section. The solid bars G are preferably three in! number, two of them being at the bottom and receiving screws g, which fasten the trough or tube E to the casing A.

The extension of the burner C beyond the rear wall of the casing A provides a space in which the gas or vapor and air already mingled in the mixing-chamber D ma more perfectly commingle before turning ack to the discharge apertures c. chamber ends approximately opposite the rear end of the series of said apertures. Water-inlet tube J and steam-outlet tube Kenter through the rear wall of the casing Aand are in continuation of the coiled water-pipe B. The iniammable gas or vapor used -in this steam l din ll hr h erator exten ongitu a t o A, parallelligburner C and tweeiigit and t e inner helix of water-tube B. Generator L is sulpplied at its protruding rear. end

with volati e hydrocarbon through an' oiltube M and at its forward end, also protruding, is supported by a bent bracket N, also by. a collar O, surroun v said generator and attached by screws o to the front wall a of said casing. The said bracket has a bore n, communicatin'at one end with the interior ofA nerator d and at the;l other viltlina jeit-hole ,arrange o tetecentr 'eo mixing-chamber lit at an interval sufcient to allow the-free inilow of air with said gas to salhhamber. f l* hn generator L consists o a ong cy drical casing or tube and a removable rod Q of similar length, provided at intervals with collars or annular shoulders g, which fit the in side of said casing. Each collar is provided with a lo 'tudinal groove or channe`l g, connecting e space Vbefore it to the space behind it,\these grooves or channels being arranged alternately on o posits sides of the generator. The spaces tween the The said mixingnerator is produced in a vapor-gen said collars constitute gas-retorts, and such construction and 'arrangement of the said grooves compels the currents of hydrocarbonl to eddy about in said retorts, the fuel being self-retarded and retained, so as to insure perfect gasifying. At each retort from rear to front it is more intensely heated, the proximity of the burner insuring no lack of additional heat-supply at any oint and the continuous effect being cumu ative. At last it issuesas a fixed gas and is delivered in this state to the jet-hole. The collared rod Q has at its rear end a shar -edged disk Z, lwhich 'serves both to close th for cleaning the interior thereof While the said rod is Withdrawn. This latter feature is very impor-tant, for my steam-generatoris adapted to use kerosene as Well as gasolene, and heavier oils, like the former produce a quantity of soot and other residuum, which would soon clog the passages g3 and stop the generation of steam unless some remed were provided. An inlet-bore m, throug the imddle of cleaning-disk Z and the roximate part of rod Q, admits the fluid fue from inleti M to the fu'st retort next to the At its outer end rod Q is provided with an operating-knob Q', also with screw-threads engaging like threads in screw-tapped racket N, through which it extends, being locked there normally by a small lockingscrew that Works against the threads q2 throng one side of said opening. The said rod is, however, easily freed by unscrewing first the said lockin -screw and then itself and may then be Withdrawn by a slight pull, thereby cleanin the interior of the generator tube or shel as stated. With equal facility it is returned to place and locked there by reversing the above procedure, and the gas-generator is then complete again.

T e jet-hole P is governed by a needlevalve R, having on its stem a toothed rack 1',

i which engages and is operated' b a Ipinion s, adjusting-rod7 S, aving a carried by a'rotary B means of said adjusting knbb or head s.

ev generator-tube and ICO rod, pinion, and rac the said valve'is readily advanced or withdrawn' more or less, as desired. The said valve-stem and adjustingrod move in and are su ported by tubular guide-arms or castings 'Upand-V at right angles to each otherl and preferablyv integral with the bracket N mental bracket or angle-iron tv supports the middle partA of arm or casting V. Both it and the first-mentioned bracket N are fastened to the front wall a of casing A by screws 'v'. A sleeve W surrounds rod S Within the tubular arm V, itslower end being in contact with inion s and its outer end-being provided a disk-form head w Within an enlargement V .of the said arm, this head bearing against shoulder V2 thereof.' The interior o said enlargement constitutes a aforesaid. A supplewall of said chamber, compressing said material on the rod S and against the head W. The sleeve Wis thereby held against the pinioii s, keeping it in engagement with the rack It by a sufficient pressure. Of course the said gland or screw-plug is centrally bored to receive the rod S. The outer end of the other tubular arm U isalso internally screwthreaded at u and closed by a screw-plug Y,

engaging therewith.

The front end of casing A is provided with an opening 1, through which a lighted match may be inserted to ignite the gas or vapor within. A pivoted disk-form cover 2 is pro vided for this opening.

For operating this generator I connect the water-inlet tube to a tank and the outlet-tube to the engineer heating apparatus, as in my Patent N o. 675,862. I then force water into the tank, compressing the air therein till there is suilicient air-pressure to feed the water through the helices to the point where steam is needed. The gas havinrT been previously ignited, the water in said ielices and the outlet-pipe continuous therewith is converted into steam, the engine begins to work, a pump on said engine pumps water into the tank, maintaining water-sup ly and air-pressure. At a certain point of t ie latter a valve in a branch pipe opens, diverting the water to a supply-reservoir, as in said patent, the pressure and feedin being automatically kept up thereafter, as described therein.

Inthe accom anyingl ydrawings I have shown but two lielices; but of course the number may be increased at will. A generator having one hundred and sixty-four feet length of water-tube in two helices, wound, res ectively, on a seven-inch. and an eight an one-fourth inch mandrel and having a half-inch. wide accumulating-space F surrounding the outer helix within. a casing A twenty-six inches long will supply five-horse power. Three helices (two hundred and sixty-two feet) similarly arranged will supply a ten-horse power, four coils (three hundred and seventy-four feet) fifteen-horse ower, five coils (four hundred and ninetyour feet) twenty-horse power. The tube is steel drawn, one-half inch diameter outside, ive-sixths inch inside; but of course I do not limit myself to the said material or dimensions, which are merely stated for a fuller exposition ofthe matter.

The gas from the jet-hole enters the open outer end of the mixing-chamber, bearing with it the intervening and surrounding air and becoming intimately mingled therewith in said chamber and at the space beyond the outer end thereof. It then flows back outside of said miXing-clniniber through vtlsc burner and jets out obliquely through the holes c, ignited against the lower parts of eacn helix, llowing around and enveloping in llame each coil or winding of each helix and iilling all the intervals between the coils and between the helices, as well as the surrounding accumulator-space I", where, and especially in the upper part thereof, the heat is so concentrated as to nearly equal the first direct action of the blaze, the gaseous fuel being almost entirely consumed. If the pres sure of the heat and expansion becomes excessive, the openings at the bottoni afford an .l outlet, which may be made to communicate with the oil tank or reservoir for maintaining automatic feeding of the fuel; but ordinarily the outflow will be slight and may be disregarded..

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In a steam-generator, the combination of a water-tube coiled in concentric helices with. a laterally-perforated burner extending longitudinally as a corewithiii the same and discharging ignited gas or vapor against the coils thereof and means for maintaining intervals between the helices for the purpose set forth.

2. In a steam-generator, the combination of a water-tube coiled into concentric approximately horizontal helices with a burner surrounded thereby extending longitudinally as a core therein, provided with a series of perforations in its under side and discliarging ignited gas or vapor against the lower parts of the coils and means for maintaining intervals between the said helices and between the coils of each helix substantially as set forth.

3. In a steam-generator, the combination of a water-tube coiled into concentric ap proximately horizontal helices with a burner surrounded thereby and discharging ignited gas or vapor against the lower part of the lIO same in oblique diverging jets'on each side of the vertical longitudinal central lane of the said burner substantially as set fiirtli.

4. In a steam-generator, the combination, of a water-tube coiled into concentric approximately horizontal helices with a burner surrounded thereby and discharging ignited gas or vapor against the lower part of the said helices in series of Obli ue diverging jets on each side of the Vertica longitudinal central plane of the said burner and heat-outlets arranged along the central line of the bottom of the generator between the series of jets for the purpose set forth.

5. In a `steam-generator, the combination of a water-tube coiled into concentric approxim ately horizontal helices with a burner surrounded thereby and discharging ignited gas or vapor against. the lower part of the said helices and an inclosing casing arranged to leave a space between it and the outer` .casing being provided with outlets at the bottom only for the purpose set forth.

7. In a steam-generator, the combination of a water-tube 4coiled into concentric approximately horizontal helices with a burner surrounded thereby andv discharging ignited gas or vapor against the lower part of the said helices, an in closing casing arranged to leave a space between it and the outer helix as an accumulator of concentrated heat and devices interposed between the said casing and the outer helix to maintain the said space unchanged and hold the said helices in position substantially as set forth.

8. In a. steam-generator, the combination of a water-tube coiled into concentricapproximately horizontal helices with a burner surrounded by the same and discharging gas or vapor in two series of diverging jets against the lower part of said heliceson each side of the vertical plane of the axis of said burner, an inclosing casing arranged to leave a heat-accumulator space between it and the outer helix and anI outlet trough or pipe ar- "rangedlongi'tudinally' under said casing between the two series of such jets, the said pipe being connected to the interior of said casing by a series of openings substantially as set forth.

9. In a steam-generator, the combination of a water-tube coiled into approximately horizontal concentric helices with a burner surrounded by the same and discharging ignited gas or. vapor in two series of diverging jets against the lower part of said helices on each side of the vertical plane of the axis of said burner an inclosing casing arranged to leave a heat-accumulator space between it and the outer helix and an outlet trough or pipe communicating with the interior of Asaid casing and arranged longitudinally'under the said casing between the two series of diverging jets and supports for said helices arranged between the outer helix and the said casing and serving to keep the intervening heataccumulator space unchanged, two of the said supports being arranged above the said pipeor trough, which is fastened to these sujliports and suspended therefrom substantia ly as set fort 10. In an approximately horizontal steamgenerator, the combination of a helical watertube with a burner surrounded thereby and discharging ignited gas or vapor against the lower part of the same, an outer casing closed at-the top but having outlet below, and longitudinal helix-supports provided with trans- -verse upward passages for heat and heated matter substantially as set forth.

1 1. In an approximately horizontal steamgenerator, the combination of a helical watertube with a burner surrounded thereby and discharging ignited gas or vapor against the lower part of the same, an outer casing closed at the top but having outlet below and longitudinal helix-supports provided with transverse upward passages and interposed between the casing and helix to maintain without change a heat-accumulator s ace between them substantially as set fort 12. In a steam-generator, the combination of a water-tube wound into approximately horizontal concentric helices, a burner surrounded thereby and discharging ignited gas or vapor against the lower part of the same throughout the length of the same, longitudinal su ports which separate the helices from each other and which are povided with grooves or projecting parts w `ch separate the coils of each helix from each other, an outer casing and additional longitudinal helix-supports, some of whichare provided with upward and downward passages, and some of which also serve to maintain an accumulator-space between the outer helix and the said casing substantially as set forth.

13. In a steam-generator, the combination of a water-tube wound in concentric-approximately horizontal helices with a burner surrounded thereby and provided with a series of holes for discharging ignited gas and vapor against the lower part of said helices throughout their length, an exterior casing arranged to leave an accumulator-space within it around the said helices and having outlet below but not above and means for maintaining intervals between the helices' and hetween the coils of each helix, as well as maintaining the said accumulator-space for the purposes set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIS MITCHELL.

Witnesses:

MARGARET A. DANIHER, CHARLEs D. WooDBERRY.

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